1. Field of the Invention
The present invention relats to an image information converting apparatus for performing an image information conversion for example a compositexe2x80x94component conversion for a television receiver or the like.
2. Description of the Related Art
In a conventional compositexe2x80x94component conversion, a composite color image signal such as an NTSC (National Television System Committee) signal is separated into a Y signal (luminance signal) and a C (chrominance) signal by a Y/C separating circuit. Thereafter, the C signal is color-demodulated to component signals Y, R-Y, and B-Y as base band signals. To obtain primary color RGB signals from the Y, R-Y, and B-Y component signals, it is necessary to perform a matrix process.
Next, with reference to FIG. 1, the overall structure of a conventional NTSC television receiver will be described. A reception antenna 201 receives a radio wave. A signal based on the received radio wave is supplied to a tuner 202. The tuner 202 selects a signal of a desired channel from the received signal and amplifies the signal of the desired channel. The amplified signal is supplied to an intermediate frequency amplifying circuit 203. The intermediate frequency amplifying circuit amplifies the received signal, generates an NATS signal with a gain properly adjusted, and supplies the NTSC signal to a Y/C separating circuit 204.
The Y/C separating circuit 204 separates the received NTSC signal into a Y signal (luminance signal) and a C (chrominance) signal. The C signal is supplied to a chrominance signal demodulating circuit 205. The Y signal is supplied to a matrix circuit 206. The chrominance signal demodulating circuit 205 color-demodulates the C signal and generates component signals R-Y and B-Y as base band signals. The generated component signals R-Y and B-Y are supplied to the matrix circuit 206. The matrix circuit 206 performs a matrix process for the received component signals R-Y and B-Y and generates primary color signals R, G, and B. The generated primary color signals R, G, and B are supplied to a CRT (Cathode Ray Tube) 207.
In the structure shown in FIG. 1, an NTSC signal as a composite image signal is processed by the Y/C separating circuit 204, the chrominance signal demodulating circuit 205, and the matrix circuit 206 so as to obtain primary color signals R, G, and B. Thus, the circuit scale of the television receiver shown in FIG. 1 is large. In addition, the image quality tends to deteriorate due to an operation error of the Y/C separating circuit. For example, a dot disturbance and a cross color take place at for example an edge of an image and a moving image section.
Therefore, an object of the present invention is to provide an image information converting apparatus that allows the circuit scale to be reduced and the image quality to be prevented from deteriorating.
A first aspect of the present invention is a converting apparatus for converting a composite color image signal having a plurality of pixels into a component color image signal composed of a plurality of components, comprising a class determination pixel extracting section for extracting a pixel at a considered point and a plurality of pixels with the same phase as the pixel at the considered point from the component color image signal, a class determining section for determining the class of the considered point based on the difference between the pixel value of the pixel at the considered point and the pixel value of each of the plurality of pixels with the same phase, and an image converting section for converting the composite color image signal into the component color image signal based on the class of the considered point determined by the class determining section.
A second aspect of the present invention is a converting method for converting a composite color image signal having a plurality of pixels into a component color image signal composed of a plurality of components, comprising the steps of (a) extracting a pixel at a considered point and a plurality of pixels with the same phase as the pixel at the considered point from the component color image signal, (b) determining the class of the considered point based on the difference between the pixel value of the pixel at the considered point and the pixel value of each of the plurality of pixels with the same phase, and (c) converting the composite color image signal into the component color image signal based on the class of the considered point determined by the class determining section.
A third aspect of the present invention is a converting apparatus for converting a composite color image signal having a plurality of pixels into a component color image signal composed of a plurality of components, comprising a class determination pixel extracting means for extracting a pixel at a considered point and a plurality of pixels with the same phase as the pixel at the considered point from the component color image signal, a class determining means for determining the class of the considered point based on the difference between the pixel value of the pixel at the considered point and the pixel value of each of the plurality of pixels with the same phase, and an image converting means for converting the composite color image signal into the component color image signal based on the class of the considered point determined by the class determining means.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings.